Unit Converter

Convert between 1,256 pairs of units across 20 categories — length, weight, temperature, volume, speed, data and more. Every conversion factor on this site is exact, and every page loads without a single external request.

Quick length converter

Switch either dropdown to convert any pair of length units, or pick a category below.

Popular unit conversions

The conversions people look up most often:

cm to inchesinches to cmkg to lbslbs to kgCelsius to FahrenheitFahrenheit to Celsiusmm to inchesinches to mmkm to milesmiles to kmmeters to feetfeet to meterscm to feetfeet to inchesinches to feetml to fl ozfl oz to mlliters to gallonsgallons to literscups to ml

All converters

• Length and Distance ConverterConvert between metric and imperial units of length — millimeters, centimeters, meters, kilometers, inches, feet, yards and miles.
• Weight and Mass ConverterConvert between kilograms, grams, pounds, ounces, stones and tons. Exact factors based on the international pound of 0.45359237 kg.
• Temperature ConverterConvert Celsius, Fahrenheit, Kelvin and Rankine. Temperature scales have different zero points, so they are converted with a formula rather than a simple ratio.
• Volume and Capacity ConverterConvert liters, milliliters, gallons, cups, fluid ounces, tablespoons and teaspoons. US and imperial measures are listed separately because they differ by about 20%.
• Area ConverterConvert square feet, square meters, acres, hectares and every other common unit of area.
• Speed and Velocity ConverterConvert miles per hour, kilometers per hour, meters per second, knots and mach. Exact factors based on the international mile and the nautical mile.
• Time ConverterConvert seconds, minutes, hours, days, weeks, months and years.
• Digital Storage ConverterConvert bytes, KB, MB, GB, TB and bits using the binary (1024) convention that operating systems report.
• Pressure ConverterConvert psi, bar, pascal, kPa, atmospheres, mmHg and torr.
• Energy and Work ConverterConvert joules, calories, kilocalories, kWh, BTU and electronvolts.
• Power ConverterConvert watts, kilowatts, horsepower, megawatts and BTU per hour.
• Torque ConverterConvert Nm to ft-lbs, in-lbs, kgf-m and back. Torque figures are what every fastener specification and wrench setting is quoted in.
• Angle ConverterConvert degrees, radians, gradians, arcminutes and arcseconds.
• Frequency ConverterConvert hertz, kilohertz, megahertz, gigahertz and RPM.
• Force ConverterConvert newtons, kilonewtons, pound-force, kilogram-force and dynes.
• Fuel Economy ConverterConvert MPG, L/100km and km/L. US and imperial gallons differ, so US MPG and UK MPG are listed separately.
• Data Transfer Rate ConverterConvert Mbps, Gbps, MB/s and other network and download speed units.
• Height Converter — Feet and Inches to cmPassport, visa and medical forms ask for height in centimetres; the US and UK still state it in feet and inches. Convert either way below.
• Stone and Pounds to kg ConverterThe UK and Ireland state body weight in stone and pounds; almost everywhere else uses kilograms. Convert either way below.
• Number Base ConverterConvert between hexadecimal, decimal, binary and octal, with arbitrary precision so 64-bit values stay exact.

Why this converter

Exact factors, not approximations. An inch is exactly 25.4 mm and a pound is exactly 0.45359237 kg by international agreement. Those definitions are used directly, and results are given to 10 significant digits.

Answers you can read. Alongside the decimal result, length conversions show the nearest 1/16 and 1/32 inch, and conversions to feet show feet and inches — the forms you actually need for woodworking, machining and stating a height.

Fast, everywhere. Each page is static HTML with the stylesheet inlined. There are no ads, no trackers, no web fonts and no external requests, so the conversion chart is on screen before a typical site has finished its first round trip.

Readable without JavaScript. The direct answer, the formula and the full conversion chart are in the HTML. JavaScript only adds live recalculation as you type.